ELI5: Explain Like I'm 5

Graphical timeline of the Big Bang

Imagine a storybook that tells the story of the universe, starting from when it was just a tiny speck. At the very beginning, there was nothing, but then suddenly there was a big flash, like a really bright light. This was the moment of the Big Bang.

Right after the Big Bang, everything was very hot and very crowded. The universe was full of particles that were packed together so tightly that they couldn't move. But as time passed, the universe got less crowded and particles were able to move around more.

As the universe continued to expand, it began to cool down. This allowed the particles to join together and form atoms, which are the building blocks of everything around us.

After about 380,000 years, the universe had cooled enough for light to travel freely through it. This light is called the Cosmic Microwave Background and it's what we see when we look out into space with special telescopes.

Over billions of years, stars and galaxies began to form. Our own sun and Earth are just a small part of this grand cosmic story.

The graphical timeline of the Big Bang shows all these events in order, like a timeline you might see in a history book. It helps us understand how the universe was formed and how everything we see around us today came to be.